From: Tom Lane <tgl@sss.pgh.pa.us>
To: Bruce Momjian <bruce@momjian.us>
cc: KES <kes-kes@yandex.ru>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Typo in doc or wrong EXCLUDE implementation
In-reply-to: <20180808130040.GA2611@momjian.us>
References: <153121527691.1408.5686988620817799073@wrigleys.postgresql.org>
 <20180807173659.GD7297@momjian.us>
 <31616681533725753@sas1-d856b3d759c7.qloud-c.yandex.net>
 <20180808130040.GA2611@momjian.us>
Comments: In-reply-to Bruce Momjian <bruce@momjian.us>
	message dated "Wed, 08 Aug 2018 09:00:40 -0400"
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Date: Wed, 08 Aug 2018 09:51:28 -0400
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Bruce Momjian <bruce@momjian.us> writes:
> On Wed, Aug  8, 2018 at 01:55:53PM +0300, KES wrote:
>> If such exclusion constraint would be marked as UNIQUE we can use it fo=
r FK while implementing temporal/bi-temporal tables.

> Yes, it would work, but doing that only for equality would be surprising
> to many people because exclusion constraints are more general than
> equality comparisons.

In general, we should be discouraging people from using EXCLUDE syntax
with simple equality operators, not encouraging them to do so.  It's
less efficient and less portable than a regular btree-based uniqueness
constraint.  So I think this proposal is a bad idea regardless of
whether it'd be technically feasible or not.

			regards, tom lane